An arrest is the act of depriving a person of his or her liberty usually in relation to the investigation and prevention of crime. The term is Anglo-Norman in origin and is related to the French word arrêt, meaning "stop".

In English law, whether a person has been arrested does not depend on the legal authority of the person enforcing the arrest, rather it depends upon whether he has been deprived of his liberty to go where he pleases.[1] Whether an arrest is lawful depends on whether the police officer or civilian exercising the arrest is acting within the scope of her or his powers.

Upon arrest a person must ordinarily be taken to a police station as soon as is practicable,[2] but may be released on bail.

The reading of the Miranda warning or similar "caution" to an arrestee advising him or her of rights is not legally required upon arrest. A legal caution is required only when a person has been taken into custody and is interrogated. Legal cautions are mandated in the US, most Commonwealth and other common law jurisdictions, and countries where the right to legal counsel, the right to silence, and the right against self-incrimination have been clearly established.

In the United Kingdom a person must be told that he is under arrest,[8] and "told in simple, non-technical language that he could understand, the essential legal and factual grounds for his arrest".[9] A person must be 'cautioned' when being arrested unless this is impractical due to the behaviour of the arrestee i.e. violence or drunkenness. The caution required in England and Wales states,

You do not have to say anything, but it may harm your defence if you do not mention when questioned something which you may later rely on in court. Anything you do say may be given in evidence.[10]

Deviation from this accepted form is permitted provided that the same information is conveyed.

Otherwise than in relation to terrorist suspects, a police constable has the following powers where he arrests a person outside a police station:[11]

Search person

Search property

Seize property

including a right to require a suspect to remove an outer coat, jacket or gloves (but nothing else) and to search the arrested person's mouth

any premises in which the person arrested was when arrested or immediately before

Danger

if the constable has reasonable grounds for believing that the arrested person may have articles that can present a danger to himself or others

if the constable has reasonable grounds for believing that the person searched might use the property to cause physical injury to himself or to any other person

Escape

to the extent that is reasonably required if the constable has reasonable grounds for believing that the person to be searched may have concealed on him anything which he might use to assist him to escape from lawful custody

other than an item subject to legal privilege, if he has reasonable grounds for believing that he might use it to assist him to escape from lawful custody

Evidence

to the extent that is reasonably required if the constable has reasonable grounds for believing that the person to be searched may have concealed on him anything which might be evidence relating to an offence

if the constable has reasonable grounds for believing that there is evidence relating to the offence for which the person has been arrested

other than an item subject to legal privilege, if he has reasonable grounds for believing that it is evidence of an offence or has been obtained in consequence of the commission of an offence

Breach of a court order can be civil contempt of court, and a warrant may issue for the person's arrest. Some court orders contain authority for a police officer to make an arrest without further order.

If a legislature lacks a quorum, many jurisdictions allow the members present the power to order a call of the house, which orders the arrest of the members who are not present. A member arrested is brought to the body's chamber to achieve a quorum. The member "arrested" does not face prosecution, but may be required to pay a fine to the legislative body.

Ordinarily only human beings can be arrested, but recent and somewhat controversial changes to criminal codes have allowed for the arrest not only of the usual "contraband, evidence, fruits, and instrumentalities" of crime, but also of inanimate objects such as money, automobiles, houses, and other personal property under asset forfeiture.

While an arrest will not necessarily lead to a criminal conviction, it may nonetheless have serious ramifications such as absence from work, social stigma, and in some cases, the legal obligation to disclose an incidence of arrest when the person applies for a job, a loan or a professional license. These collateral consequences are more severe in the United States than in the UK, where arrests without conviction are not usually considered significant and are not even recorded in a standard criminal record check. In the US, a person who was not found guilty after an arrest can remove his arrest record through an expungement or Finding of Factual Innocence. A legal action is sometimes filed against the government for wrongful arrest.